1. Field of the Invention
This invention relates to hearing aids and more particularly to an ear mold for a hearing aid which incorporates a plurality of reflection and resonance chambers.
2. Description of the Prior Art
Heretofore, hearing aids have been developed for amplifying sound waves and to conduct the amplified waves to the tympanic membrane of the ear, in order to improve the hearing of an individual. Presently manufactured hearing aid apparatus includes an amplifier, transducer, and an ear mold, all of parts of which are insertable into the ear.
Amplified sound wave energy created by the amplifier and transducer is usually air conducted to the ear mold, wherein the longitudinal canal or conduit conveys the amplified sound wave energy to the tympanic membrane of the ear, where the normal hearing process is commenced. That is, the sound energy strikes the tympanic membrane and then travels onto the malleus, the incus, the stapes, to the oval window, and on through the fluid of the inner ear, where the cochlea contains the Organ of Corti with associated nerve endings of the auditory nerve from the brain.
A disadvantage of the presently manufactured ear molds is that improved hearing is contingent solely upon sound wave amplification. If, for example, otosclerosis has rendered immovable, or partially immovable, the stapes due to ankylosis in the oval window, the effectiveness of a hearing aid is lost. Also, in many instances where a high level amplification is necessary, sound saturation results, whereby the normal process is not aided insofar as intelligibility is concerned.
In addition to the normal air conduction process of hearing by way of the tympanic membrane, sound wave energy can also be conducted to the hearing part of the brain by means of bone conduction. In bone conduction hearing, vibratory sound wave energy is transmitted to the brain over a separate and distinct route from the normal hearing process. Sound wave energy directly enters the mastoid process and other associated bones of the head and travels by bone conduction to the hearing part of the brain for discrimination and interpretation. Thus bone conduction hearing can be beneficial in reinforcing sound wave energy transmitted to the brain by the normal air conduction process.